Toxicity of dipterex in a fish pond ecosystem | |
| Author | Pham Anh Tuan |
| Call Number | AIT Thesis no. AE-92-29 |
| Subject(s) | Fish ponds Biotic communities |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | A series of short term toxicity tests of an organophosphate insecticide dipterex (2,2,2- trichloro-1-hydroxylthylphosphate) on Nile tilapia (Oreochromis niloticus), Hoina, Chlorella were carried out under laboratory conditions. 24-h , 48-h, 72-h and 96- h LC50 for tilapia averaging 0.6 g at 24 - 29oC, pH: 7.5 - 7.8 were 3.98 ppm, 2.09 ppm, 1.57 pmm and 1.43 ppm, respectively. While 12- h, 24-h LC50 values for Hoina were 2.09 ppm and 0.64 ppm . The safe concentration of dipterex for 0. nilotious was estimated as 0.173 ppm. A reduction in net primary productivity of pure cultured Chlorella in 3 .5 ppm and 5 ppm dipterex were investigated; in these two concentrations, net productivities of the algae were 80.2% and 62 .5% as compared to that of the control . A long- term test of 10 weeks with tilapia cultured in tanks, including 6 treatments with three replicates each, was conducted in order to investigate long term effects of dipterex application on a fish pond ecosystem. The highest values of dissolved oxygen and the lowest N02 - N concentrations were recorded from 3.5 ppm and 5 ppm dipterex treatment (P<0.05). However , there was no direct effect of dipterex on water quality . Chlorophyll-a concentrations were not decreased after al l dipterex administrations, although a reduction in n et primary productivity was observed in 3.5 ppm and 5 ppm treatments at the second and the third administration. The number of total zooplankton, as well as copepod nauplii, was decreased after each dipterex treatment in all concentrations. In contrast, there was no evidence of a reduction in number of Brachionus. Fish mortality was recorded in all dipterex treatments fol lowing the first administration. Lower mortality was observed after the later dipterex administrations. The re was a highly significant difference (P <0.01) in fish biomass, after the first dipterex administration through to the e nd of test. The lowest fish biomass was in 3.5 ppm and 5 ppm dipterex treatments. An additional experiment was carried out to investigate the direct effects of clipterex administration on dissolved oxygen concentration, however, no conclusion concerned with this matter could be reached. Based on the present study , ppm or below was recommended as containing Nile tilapia. |
| Year | 1992 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Phillips, Michael J. |
| Examination Committee(s) | Lin, Chang Kwei ;Knud-Hansen, Christopher F. |
| Scholarship Donor(s) | The Government of New Zealand; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1992 |